The present invention relates to a brake system as defined hereinafter.
Such brake systems are well known and described in many publications. As an example, Bosch Technische Berichte [Bosch Technical Reports] of February, 1982, ISSN 0006-789X can be named, page 17 of which mentions the so-called anti-skid braking system ABS 2S.
In this known system, an undamped feedback of the anti-skid control on the brake pedal takes place, and the driver perceives this feedback as unpleasant. German Offenlegungsschrift 31 07 963 already shows a brake system in which a total suppression of the feedback is performed. There, a hydraulic tank receives brake fluid from the wheel cylinders via a control valve, and as a result the brake pressure is lowered. This brake fluid is removed from the hydraulic tank to a reservoir via a fluid pump. However, this arrangement has the disadvantage that the return pump pumps toward a high-pressure reservoir, so the corresponding reservoir chamber must receive the entire volume in the circuit. This causes problems in terms of safety. The pressure reduction is also limited by the spring force of the reservoir; that is, a reduction to very low pressure values, such as 0.5 to 1 bar, is impossible.